Published May 09, 2023 by

Blood In Urine: Hematuria



The presence of blood in the urine is a finding that usually causes great concern in patients. It is obvious to everyone that the loss of blood in the urine is not a normal event. In general, a reddish or dark colored urine usually indicates that there is something wrong with the genitourinary system.

Bloody urine is called hematuria by doctors. Hematuria can not always be detected by the naked eye. In some cases, the amount of red blood cells (red blood cells) is so small that it is only possible to detect it through urine tests.

A wide variety of illnesses can cause bloody urine to leak. In most cases, hematuria is usually one of the signs of a urinary tract infection. However, the existence of blood in the urine can also be a sign of serious illness, such as bladder or kidney cancer, or have no special significance, occurring due to discrete defects in the renal tubules, which have no clinical relevance.

What is hematuria?

The simplest definition of hematuria is: presence of blood in the urine.

However, in most situations, the patient with hematuria does not present with frankly bloody, reddish urine or with visible clots. In many cases, the loss of blood in the urinary tract is so slight that it is not possible to notice the presence of blood in the urine just by looking at it. In addition, the presence of other substances in the urine, such as bilirubin, medications, dyes, myoglobin, etc., can also make the urine red, giving the false impression of having hematuria (read: Colored urine).

Therefore, in order to define with certainty that a urine contains blood, it is necessary to submit it to laboratory analysis. The most commonly used urine test for diagnosing hematuria is the EAS (also called urine type 1 or urine type 2).

The main blood cell is the red blood cell (also called erythrocyte or red blood cell). The laboratory investigation of hematuria consists of evaluating the urine with a microscope, looking for red blood cells. All urine contains minute amounts of red blood cells. To be considered hematuria, most laboratories use as a reference the existence of more than 10,000 red blood cells per milliliter of urine or more than 5 red blood cells per high-power field (field seen with a 400x magnification lens).


As there are dozens of causes for the presence of blood in the urine, the characterization of the same helps in clinical investigation. Hematuria can have the following characteristics:

Macroscopic hematuria

It is the hematuria that can be seen with the naked eye, as the urine is darkened, reddish or with blood clots. This type of hematuria is easily recognized by the patient himself.

Microscopic hematuria

It is hematuria that cannot be seen with the naked eye. The appearance of the urine is completely normal, with the presence of blood only being detected by urinalysis. This type of hematuria can exist for years without the patient being aware of the fact.

With clots

Hematuria with clots is a type of macroscopic hematuria. The presence of clots usually indicates a larger volume of bleeding, caused by an injury to the genitourinary tract, which can often be identified through imaging tests, such as ultrasound or computed tomography.

Persistent or Transient

Hematuria, whether macroscopic or microscopic, can be persistent, that is, it is constantly present; or be intermittent, that is, appear and disappear from time to time. 

Dysmorphic hematuria

Dysmorphic hematuria occurs when the urine test detects erythrocytes with an atypical shape (dysmorphic). This is usually a sign of disease of the renal glomeruli.

Isolated hematuria

Isolated hematuria occurs when the patient has no other signs or symptoms other than the presence of blood in the urine. Most diseases that cause hematuria cause symptoms such as painful urination, fever, back pain, or other changes in laboratory tests, such as the presence of proteins and/or leukocytes in the urine, elevation of creatinine and urea in the blood, etc.

The presence of blood in the urine, when it occurs without any other signs or symptoms and with persistently normal laboratory tests, usually indicates a benign disease.

Hematuria is always a bad sign

Hematuria may not be a bad sign in the following cases:

– Can be detected in urine during menstruation.

– It can be detected during a common urinary tract infection
– Sometimes certain medications and foods can cause the urine to be colored a redder shade, as already mentioned above.
– When this happens after intense physical exercise of the body
– Some people have abnormal hematuria that is not related to kidney or urinary tract disease.


Hematuria can be located anywhere in the urinary tract, including the kidneys, ureter, bladder, prostate, or urethra. Some causes of urinary bleeding are:

Bladder infection, such as cystitis (link to cystitis), which in most cases causes a burning sensation during urination.

Kidney infection, which can also cause high fever and pain in the side of the abdomen.

Kidney stones, which may not cause pain but can sometimes block the flow of urine in the tubes that pass through the kidneys (ureters) and be very painful.

Bladder tumor that usually occurs in people over the age of 50 and can cause the need to urinate more frequently and urgently as well as pain when urinating.

Kidney tumor that also affects older women and can cause constant pain under the ribs and abdomen.

Some inflammation such as nephropathy, nephritis, systemic lupus erythematosus, etc UTI, which can be just a common bladder infection and cause hematuria.

Some more causes are:

Kidney cancer.
Bladder cancer.
Prostate cancer.
Kidney calculus.
Urinary infection.
Benign prostatic hyperplasia. Glomerulonephritis.
Sickle cell anaemia.
Kidney polycystic disease.
Accidents with renal trauma.
Trauma after passing a urinary catheter.
Trauma from surgical or endoscopic manipulation of the urinary system.
Prostate biopsy.
Kidney biopsy.
Radical cystitis (injury to the bladder by radiotherapy).
Urinary tuberculosis.
Physical effort.
Excess calcium in the urine.
Excessive anticoagulation.

Note: some medications, such as pyridium, rifampicin, phenytoin and nitrofurantoin, or foods, such as beetroot, can make the urine red without this meaning the presence of blood.

Detection of hematuria – What tests should be done

Blood tests are done to check for low blood counts and anemia and to determine if the kidneys are functioning normally. Kidneys are also examined for possible tumors and cysts by means of an ultrasound. A special test called a cystoscopy may sometimes be needed. This test uses a small camera attached to the end of a rubber tube to examine the walls of the bladder. This specific examination can be performed through simple local anesthesi. In many cases and if the causes of hematuria cannot be established through the classic tests, a cytological examination of the urine is performed, which can be particularly useful.

If after the tests it is found that the blood comes from the kidneys, then a kidney biopsy is recommended. This involves taking a tissue from the kidney and examining it under a microscope.


As we can see above, the causes of blood in the urine are multiple and, therefore, the investigation is not always simple and quick.

In the case of women with microscopic hematuria, the first step is to confirm that the urine was not collected during menstruation. During the menstrual period there is always a little blood from menstruation in the urine, causing false hematuria. In these cases, the urine test needs to be redone outside menstruation for confirmation.

Sometimes, signs and symptoms that accompany hematuria can suggest the diagnosis, for example:

1.Young women with burning urination and hematuria probably have cystitis.

2.Patients with hematuria accompanied by fever, chills, vomiting, and back pain possibly have pyelonephritis.

3.Hematuria accompanied by excruciating lower back pain radiating to the groin is usually a sign of kidney stones.

4.Elderly men with hematuria and a weak urinary stream should always be investigated for prostate disease.

5. In people over 50 years old, smokers and with macroscopic hematuria, bladder cancer should always be considered.

When there is no apparent cause for hematuria, a more complex investigation begins, trying to rule out or confirm some of the various causes mentioned above.

Some of the exams that can be used in the investigation are ultrasonography, computed tomography or cystoscopy. Other blood and urine laboratory tests also help in the differential diagnosis. In some cases of hematuria, especially if there is suspicion of disease of the renal glomeruli, renal biopsy may be indicated.

Treatment of hematuria

Hematuria as a symptom is not amenable to treatment with the aim of stopping the blood flow, but with the aim of determining the causes that cause it and treating them. The treatment of hematuria depends each time on the cause that causes it. Any sign of hematuria is usually a manifestation of some disease of the urinary system and for this, medical help and treatment is needed immediately.

Thin membrane disease

In some cases of isolated hematuria it is not possible to identify a cause. If the patient has no other complaints and all tests are normal, an annual or biennial follow-up just to see if everything is fine is the only procedure indicated in these cases.